This invention relates to the art of paint primer-surfacer compositions, and more particularly, to a nitrocellulose-free primer-surfacer comprising an acrylic polymer vehicle or binder.
Primer and primer-surfacer compositions are known, particularly in the automotive industry and are applied over metal and/or plastic substrates in order to provide intercoat adhesion between the surface of the substrate and the decorative/protective top coat. Primer-surfacers also perform an additional function of filling minor flaws in the surface of the substrate which, upon sanding of the primer-surfacer, renders a smooth surface for application of the top coat. Such primer surfacers usually require a number of coats in order to attain the desired thickness of coating to cover minor surface imperfections and allow for sanding which also enhances top coat adhesion.
Until recently, nitrocellulose was the main binder ingredient in prior art primer surfacers. Because of the expense as well as the hazards involved in the use of nitrocellulose, several formulations have been developed as substitutes for nitrocellulose. Typical formulations include epoxy-terminated polyester complexes, aziridinyl-terminated esters, amine-modified acrylic resins and combinations of these polymers. Patents illustrating these types of formulations include U.S. Pat. Nos. 3,272,647 to Swanson et al, 3,345,388 to Yocum, 3,505,269 to Jeffery et al, 3,509,086 to Rohrbacher, 3,627,779 to Sandsteadt, 3,666,710 to Makhlouf et al, 3,746,673 to Simms et al, 3,962,369 to Chang et al and 4,042,539 to Fanning.
Although the above primer-surfacer formulations are of high quality and have found market acceptance, their efficiency with regard to drying time, number of coats required to fill to a smooth surface, corrosion resistance, solvent emmissions and intercoat adhesion require improvement.